The invention generally relates to endoscopes.
Such endoscopes are used, for example, in minimally invasive interventions in arthroscopy, laparoscopy and thoracoscopy, for inguinal hernias, and in operations on the joints and spinal column. The endoscopes help the operating surgeon carry out the operation, by providing a range of view as large as possible of the operating site.
During such operations, these instruments have to be able to be introduced into the operating site through extremely small access routes. This requires the use of instruments that are as slender as possible.
Such an endoscope has an elongate shaft. This elongate shaft comprises two tubes pushed one inside the other. The diameter of the inner tube is chosen such that it is radially spaced apart from the outer tube. A channel is thereby formed between the inner and outer tubes. This channel is used to receive a light guide, which is formed by a large number of glass fibers.
A distal end of the shaft is beveled, and a correspondingly worked lens is fitted on distally. This arrangement ensures that the operating site can be seen through the lens at a viewing angle of 30° or 70°, for example, relative to the central longitudinal axis of the endoscope.
The shaft is received with its proximal end in an endoscope head. The inner tube can in this case extend into an internal bushing of the endoscope head. The proximal end of the outer tube of the shaft terminates in the endoscope head in such a way that the channel leads through a hollow space to a light guide connection in the endoscope head.
This light guide connection is arranged in the endoscope head, transverse to the longitudinal axis of the shaft, and has a central opening. Thus, the channel continues uninterrupted from the distal end to the proximal end of the shaft.
By means of a light guide, for example a glass fiber bundle, arranged in the channel, it is therefore possible to guide light through this channel in order to illuminate the operating site.
An eyepiece can also be mounted on the endoscope head so that an operating surgeon is able to comfortably view the operating site through the eyepiece and the shaft. For this purpose, a set of lenses or rod lenses is arranged in the inner tube. Instead of an eyepiece for direct viewing through the endoscope, a video camera can also be provided at the proximal end, and its image signals can be displayed on a monitor.
During an operation, it can happen that the operating surgeon has to change the position of the endoscope in order to be able to view the operating site from another angle. In some circumstances, forces may then act laterally or obliquely on the endoscope shaft, with the result that the shaft bends slightly. The proximal part of the shaft is particularly affected by bending.
It is regarded as being particularly disadvantageous that substantial bending of the shaft can cause the rod lenses to fracture. However, even less substantial bending can be enough to cause the glass fibers in the channel to break. Such damage to the endoscope entails at least a limited function, through weakening of the light guidance. If, in addition, a rod lens were to break, this would render the endoscope completely unusable. Damage of this kind is a particularly serious disadvantage during an operation.
From document DE 103 07 903 A1, a method for mounting an endoscope as well as such an endoscope is known. The shaft of this known endoscope comprises an outer tube in which an inner tube for receiving the imaging optics is arranged. The light guides arranged between the inner and outer tubes are received in a flexible host.
In document U.S. Pat. No. 4,790,295, there is described an endoscope, the shaft of which comprises an outer tube. An inner tube is arranged inside the outer tube for leading through forceps. Further, a short intermediate tube serving as a lens frame, is received within the outer tube distally. Image guiding elements are arranged in the lens frame. The light guides are arranged between the inner and the outer tubes. The intermediate tube configured as lens frame does not surround the inner tube.
From document DE 10 2004 008 458 A1, a method for fixing glass fibers in an endoscope is known. The shaft of this endoscope comprises an outer tube. An inner tube configured as optics tube is arranged within the outer tube, in which inner tube image guiding elements are arranged. Glass fiber bundles for guiding light extend between the both tubes.
Finally, from document DE 199 28 289 A1, an endoscope is known the shaft of which comprises an outer tube. Two inner tubes, namely a working tube for irrigation liquids and an optics tube for receiving image guiding elements, are arranged within the outer tube. Light guide fibers for guiding light are arranged between the optics tube, the working tube and the outer tube.
With all known endoscopes described above, the disadvantage continues to exist that the glass fibers of the light guide or lenses are not sufficiently protected against fracture.